The present invention relates generally to communications by a communication station in a radio communication system operable pursuant to a first communication standard, such as the IEEE 802.11 standard, in which the frequency band available for use by the system is also utilizable by another radio communication system, operable pursuant to another communication standard. More particularly, the present invention relates to apparatus, and an associated method, by which to identify, at least in a measurement summary, whether communication activity pursuant to the first communication standard is ongoing at a portion of the frequency band to which the communication station is tuned. When implemented in a communication station operable pursuant to the IEEE 802.11 standard in the 5 GHz frequency band, a measurement summary field is formed that indicates whether the communication station is tuned to a portion of the frequency band upon which 802.11-formatted data is communicated. By identifying whether the communication station is tuned to a portion of the frequency band upon which the 802.11-formatted data is communicated, subsequent retuning or communication operations at the portion of the frequency band to which the communication station is tuned is effectuated.
Advancements in communication technologies have permitted the introduction, and popularization, of new types of communication systems. In various of such new types of communication systems, the rate of data transmission and the corresponding amount of data permitted to be communicated, has increased relative to existing types of communication systems.
New types of radio communication systems are exemplary of communication systems that have been made possible as a result of advancements in communication technologies. Communication channels of a radio communication system are formed upon radio-links, thereby obviating the need for conventional wire-line connections between sending and receiving stations operable therein. A radio communication system, therefore, inherently permits increased communication mobility in contrast to conventional wire-line systems.
Bandwidth limitations sometimes limit the communication capacity of the communication system. That is to say, the bandwidth capacity of the communication channel, or channels, available to a communication system to communicate information between sending and receiving stations is sometimes limited. And, the limited capacity of the communication channel, or channels, limits increase of the communication capacity of the communication system. The communication capacity of the radio communication system is particularly susceptible to capacity limitation resulting from communication channel bandwidth limitations. Generally, a radio communication system is allocated a limited portion of the electromagnetic spectrum upon which to define communication channels. Communication capacity increase of a radio communication system is, therefore, sometimes limited by such allocation. Increase of the communication capacity of the radio communication system, therefore, is sometimes only possible if the efficiency by which the allocated spectrum is used is increased.
Digital communication techniques provide a manner by which the bandwidth efficiency of communications in the communication system may be increased. Because of the particular need in a radio communication system to efficiently utilize the spectrum allocated in such a system, the use of digital communication techniques is particularly advantageously implemented therein.
When digital communication techniques are used, information that is to be communicated is digitized. In one technique, the digitized information is formatted into packets, and the packets are communicated to effectuate the communication. Individual ones, or groups, of the packets of data can be communicated at discrete intervals, and, once communicated, can be concatenated together to recreate the informational content contained therein.
Because packets of data can be communicated at the discrete intervals, a communication channel need not be dedicated solely for the communication of packet data generated by one sending station for communication to one receiving station, in contrast to conventional requirements of circuit-switched communications. Instead, a single channel can be shared amongst a plurality of different sending and receiving station-pairs. Because a single channel can be utilized to effectuate communications by the plurality of pairs of communication stations, improved communication capacity is possible. Packet data communications are effectuated, for instance, in conventional LANs (local area networks). Wireless networks, operable in manners analogous to wired LANs have also been developed and are utilized to communicate packets of data over a radio link, thereby to effectuate communications between a sending station and a receiving station connected by way of the radio link.
For example, an IEEE (Institute of Electrical and Electronic Engineers) 802.11 standard defines a system for operation of a wireless LAN. The system is defined in terms of logical layer levels, and operational parameters of the various layers of the system are defined in the standard.
Proposals have been set forth to utilize an unlicensed band located at 5 GHz and to implement a WLAN operable generally pursuant to the IEEE 802.11 standard.
Other systems are also implementable at the 5 GHz frequency band. A radio communication system, referred to as the HyperLan II system is, for instance, also implemented at the 5 GHz band. The HyperLan II system is operable pursuant to a standard promulgated by the ETSI. The HyperLan II system also is a WLAN system.
As more than one communication system is operable upon common frequency portions of the 5 GHz band, communication systems operable therein must be able to dynamically select the frequency band portions upon which communications are effectuated. Dynamic selection is required so that more than one communication system does not concurrently use the same frequencies to attempt to effectuate communications.
The European Regulatory Commission (ERC) has set forth system requirements of systems operable in the 5 GHz frequency band. For instance, amongst the requirements include a requirement that a system operable at the 5 GHz band generate electromagnetic energy emissions which are spread over available frequency channels defined therein. That is, the interference level formed of the communication signal energy generated during operation of the communication system must be approximately constant over a large bandwidth of the frequency band. The interference must be spread equally and must avoid interfering with communications in satellite and radar systems.
And, for instance, an IEEE802.11 or HyperLAN system requires that a mobile station (STA) be capable of tuning to a frequency portion of the frequency band not currently used by a basic service set (BSS). And, once tuned thereto, the mobile station is required to measure for the presence of interference. Once the measurement is made, a report of the measurement must be returned to an access point (AP) of the basic service set. This procedure is referred to as dynamic frequency selection (DFS), as a result of analysis of the measurements, an access point of the basic service set determines whether to select a new frequency range for operation of the mobile station. This procedure is referred to as dynamic frequency selection (DFS). In a HyperLan II system, mobile stations report indications of a received signal strength indication (RSSI) block in a base band transceiver system as part of a DSF mechanism. Use of an RSSI indication, however, fails to provide an indication as to the source of interfering signals.
A manner better able to facilitate dynamic frequency selection in a mobile station operable in an IEEE 802.11 system would be advantageous.
It is in light of this background information related to operation of a radio communication system in which dynamic frequency allocation is utilized that the significant improvements of the present invention have evolved.
The present invention, accordingly, advantageously provides apparatus, and an associated method, for use in a radio communication system operable pursuant to a first communication standard, such as the IEEE 802.11 standard, in which the frequency band available for use by the system is also utilizable by another communication system operable pursuant to another communication system standard.
Through operation of an embodiment of the present invention, a manner is provided by which to identify, at least in a measurement summary, whether communication activity pursuant to the first communication standard is ongoing upon a portion of the frequency band to which the communication station is tuned. By providing the measurement summary, decisions are better able to be made regarding subsequent retuning or subsequent communication operations of the communication station. And, thereby dynamic frequency selection is facilitated.
In one aspect of the present invention, a measurement summary field is formed by a mobile station (STA) operable pursuant, generally, to the IEEE 802.11 standard in the 5 GHz frequency band. The measurement summary field is of a value that indicates whether the mobile station is tuned to a portion of the frequency band upon which 802.11-data is communicated. By communicating the measurement summary field to a control device, such as an access point (AP) operable in the 802.11 system, decisions are made regarding whether to retune the mobile station or to commence communications upon the portion of the frequency band at which the mobile station is tuned.
In another aspect of the present invention, the measurement summary field is populated with a value to indicate whether the mobile station is tuned to a frequency range upon which 802.11 data packets are communicated. If 802.11 data packets are communicated at the frequency range to which the mobile station is tuned, the measurement summary field is populated with a first value. If, conversely, 802.11 data packets are not communicated at the frequency range to which the mobile station is tuned, the measurement summary field is of another value. A measurement summary including the measurement summary field is communicated by the mobile station to an access point at which control functions are performed to control subsequent operation of the mobile station.
In another aspect of the present invention, once the mobile station is tuned to a selected frequency range, measurement is made of communication energy communicated at the frequency range. If communication energy is detected, the communication energy is decoded to detect whether the communication energy forms packet-formatted data. If packet formatted data is detected, further analysis of a data packet is made to determine whether the data packet is an 802.11-formatted data packet. Upon such detection, the measurement summary field is populated with a value indicating the frequency range to which the mobile station is tuned to have 802.11-formatted data packets communicated thereon. Otherwise, an indication is populated in the measurement summary field to indicate that 802.11-formatted data is not communicated upon the frequency range to which the mobile station is tuned.
In another aspect of the present invention, upon detection of the communication energy, and decoding thereof to detect the presence of a data packet, further analysis is made to identify whether the data packet is an 802.11-formatted data packet or, relative to the 802.11 standard, a foreign PLCP (physical layer convergence protocol)-formatted packet. Determination of the data packet-type is made through analysis of the packet at the physical layer and logical layer above the physical layer by which the communication system in which the mobile station is operable. In an 802.11 system, a valid packet is determined by proper decoding of the signal field, cyclic redundancy check (CRD) on the physical layer protocol data units (PPDU) and valid MAC address format. In contrast, a HyperLan II data packet does not have a corresponding 802.11-formatted data structure. Thereby, differentiation between a HyperLan II-formatted data packet and an 802.11-formatted data packet is made.
In one implementation, apparatus, and method, is provided for a mobile station operable in an IEEE 802.11 WLAN. The mobile station tunes to a frequency range within the 5 GHz frequency band. Once tuned to the frequency range, a CCA (clear channel assessment) operation is performed. A determination is made whether the CCA indicates the frequency range to be busy. The determination is made by detecting whether communication energy is present on the frequencies to which the mobile station is tuned. If communication energy is detected to be present, the mobile station further determines whether the communication energy forms a data packet which is formatted pursuant to the IEEE 802.11 standard. To make this determination, decoding operations are performed to detect a preamble portion of a data packet. If a preamble portion of a data packet is detected, further decoding operations are performed upon a signal field portion of the data packet. Subsequent to such decoding, further inquiry of the data packet is made to check to where the data packet is addressed. If a MAC ID (identifier) is detected, then the data packet is a 802.11-formatted data packet. As a HyperLan II-formatted data packet does not have a corresponding 802.11 formatted signal field (i.e., PLCP header) and MAC identifier, operation of an embodiment of the present invention is able to distinguish between a HyperLan II-formatted data packet and an 802.11-formatted data packet.
In these and other aspects, therefore, apparatus, and an associated method, is provided for a first radio communication system in which a selected portion of a frequency band is dynamically selectable upon which to communicate a first-system-type data packet. The frequency band is also selectably utilized by a second radio communication system upon which selectably to communicate a second-system-type data packet. Reporting upon whether the portion of the frequency band to which a communication station is tuned is being used to communicate the first-system-type data packet is performed. An indicator is at least coupled to receive an indication of a determination of whether the first-system-type data packet is communicated upon the portion of the frequency band to which the communication station is tuned. The indicator generates an indication signal representative of the determination. A reporter is coupled to receive the indication signal generated by the indicator. The reporter generates a report message that includes a field populated with a value indicative of the indication signal generated by the indicator.